Câu Hỏi Phỏng Vấn SQL Server và Câu Trả Lời

If you are looking forward to crack SQL Server interviews then you are at the right course.

Working in SQL Server and cracking SQL Server interviews are different ball game. Normally SQL Server professionals work on repetitive tasks like back ups , custom reporting and so on. So when they are asked simple questions like  Normalization , types of triggers they FUMBLE.

Its not that they do not know the answer , its just that they need a revision. That's what this course exactly does. Its prepares you for SQL Server interview in 2 days.

Below are the list of questions with answers , demonstration and detailed explanation. Happy learning. Happy job hunting.

Must and Basic Questions on SQL Server - Part 1

• Question 1  :- Explain normalization ?

• Question 2  :- How to implement normalization ?

• Question 3  :- What is denormalization ?

• Question 4  :- Explain OLTP vs OLAP ?

• Question 5  :- Explain 1st,2nd and 3rd Normal form ?

• Question 6  :- Primary Key vs Unique key ?

• Question 7  :- Differentiate between Char vs Varchar ?

• Question 8  :- Differentiate between Char vs NChar ?

• Question 9  :- Whats the size of Char vs NChar ?

• Question 10 :- What is the use of Index ?

• Question 11 :- How does it make search faster?

• Question 12 :- What are the two types of Indexes ?

• Question 13 :- Clustered vs Non-Clustered index

• Question 14 :- Function vs Stored Procedures

• Question 15 :- What are triggers and why do you need it ?

• Question 16 :- What are types of triggers ?

• Question 17 :- Differentiate between After trigger vs Instead Of ?

• Question 18 :- What is need of Identity ?

• Question 19 :- Explain transactions and how to implement it ?

• Question 20 :- What are inner joins ?

• Question 21 :- Explain Left join ?

• Question 22 :- Explain Right join ?

• Question 23 :- Explain Full outer joins ?

• Question 24 :- Explain Cross joins ?

Interview Questions around essential concepts of SQL Server - Part 2

• Question 25:-Why do we need UNION ?

• Question 26:-Differentiate between Union vs Union All ?

• Question 27:-can we have unequal columns in Union?

• Question 28:-Can column have different data types in Union ?

• Question 29:- Which Aggregate function have you used ?

• Question 30:- When to use Group by ?

• Question 31:- Can we select column which is not part of group by ?

• Question 32:- What is having clause ?

• Question 33:- Having clause vs Where clause

• Question 34:- How can we sort records ?

• Question 35:- Whats the default sort ?

• Question 36:- How can we remove duplicates ?

• Question 37:- Select the first top X records ?

• Question 38:- How to handle NULLS ?

• Question 39:- What is use of wild cards ?

• Question 40:- What is the use of Alias ?

• Question 41:- How to write a case statement ?

• Question 42:- What is self reference tables ?

• Question 43:- What is self join ?

• Question 44:- Explain the between clause ?

Important questions on SubQuery and Cor-related Queries in SQL-Part 3

• Question 45:- Explain SubQuery?

• Question 46:- Can inner Subquery return multiple results?

• Question 47:- What is Co-related Query?

• Question 48:- Differentiate between Joins and SubQuery?

• Question 49:- Performance Joins vs SubQuery?

How to Find Nth Highest Salary ? - Part 4

• Question 50:- Find NTH Highest Salary in SQL.

Covered Questions on finding Nth highest using co-related & TSQL-Part 5

• Question 51:-  Select the top nth highest salary using correlated Queries?

• Question 52:-  Select top nth using using TSQL

• Question 53:-  Performance comparison of all the methods.

Questions around SQL Server CTE(Common Table Expressions) - Part6

• Question 54 :- What is CTE ?

• Question 55 :- Can we execute CTE multiple times ?

• Question 56 :- What is use of CTE ?

• Question 57 :- How to write a recursive CTE ?

• Question 58 :- Can we see some real world examples of CTE ?

• Question 59 :- Can we perform insert updates on CTE?

• Question 60 :- Does is update the tables physically ?

• Question 61 :- What are temporary tables?

• Question 62 :- Temp tables vs CTE

• Question 63 :- Performance CTE vs Temp

Questions around Window functions, Rank, Dense_Rank and RowNumber - Part 7

• Question 64 :- What are window functions in SQL ?

• Question 65 :- What does partition clause in window function ?

• Question 66 :- So is window function partition similar to group by ?

• Question 67 :- What is difference between Rank vs Dense_Rank ?

Questions around Delete Duplicate Records scenarios - Part 8

• Question 68 :- Find records which are unique.

• Question 69 :- Delete Duplicate Records (with Id).

• Question 70 :- Delete Duplicate Records (without Id).

• Question 71 :- Delete Duplicate Records (using CTE).

• Question 72 :- Delete Millions of Duplicate Records without performance impact.